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Miniature swine model of phototoxicity testing
Author(s) -
Leigh Heinz,
Forbes Paul Donald,
Lawson Charles,
Kim Dae Young,
White David,
Brown Larry D.,
Wehmeier Dean R.,
Liu Jason,
Bouchard Guy F.
Publication year - 2011
Publication title -
photodermatology, photoimmunology and photomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.736
H-Index - 60
eISSN - 1600-0781
pISSN - 0905-4383
DOI - 10.1111/j.1600-0781.2011.00633.x
Subject(s) - phototoxicity , erythema , dermatology , chemistry , nuclear medicine , medicine , biochemistry , in vitro
Summary Background/Purpose This study determined the threshold doses for ‘solar erythema’ and for phototoxic responses to 8‐methoxypsoralen (8‐ MOP ) in white skin H anford and grey skin Y ucatan miniature swine. Methods For threshold erythema determinations, the UVR exposures included both UVA (315–400 nm) and UVB (290–315 nm) radiation by positioning one fluorescent ‘sunlamp’ among 10 ‘ PUVA ’ lamps. With this configuration the UVR exposures ranged from 0.5–2.8 times the ‘instrumental MED ’ ( MEDi ) for H anford and from 1.0–5.6 times the MEDi for Y ucatan. For phototoxicity determinations (i.e., with and without topically‐applied graduated concentrations of 8‐ MOP ), the UVB component was minimized by extinguishing the sunlamp, thus permitting higher UVA exposures. Results The Hanford had the lower UV erythema dose threshold (1.0–1.4 times the MEDi ) and the erythema that developed was readily observable. The exposure doses for the phototoxicity test were 5 J /cm 2 of UVA in 35 minutes or 10 J /cm 2 in 70 minutes. The phototoxic (vascular) response to 8‐ MOP was observed in the two highest concentrations (0.01% and 0.1%) in H anford pigs, in a dose‐related manner. Microscopic evidence of a dose‐related response was also observed as the concentration of 8‐ MOP increased. Conclusion This verified that the H anford miniature swine is the preferable strain for phototoxic effects. In contrast, UVR exposure of the Y ucatan pig skin produced tanning rather than erythema, confirming that the Y ucatan is the more appropriate strain for studying the melanization response. Thus, H anford and Y ucatan miniature swine have cutaneous photobiological responses that reflect their respective strain differences.